Clinical and radiological outcomes of the Eminent Spine King Cobra anterior cervical plate: retrospective evaluation of outcome

Clinical and radiological outcomes of the Eminent Spine King Cobra® anterior cervical plate: retrospective evaluation of outcome. Stephen P. Courtney,...
Author: Douglas Walker
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Clinical and radiological outcomes of the Eminent Spine King Cobra® anterior cervical plate: retrospective evaluation of outcome. Stephen P. Courtney, MD Plano Orthopedic Sports Medicine and Spine Center

INTRODUCTION: Anterior Cervical Interbody Fusion is an accepted treatment for cervical disc herniation and stenosis, discogenic neck pain, trauma, and other conditions. The Eminent Spine (ES®) Anterior Cervical Plate (King Cobra®) can be used in conjunction with the ES® Cervical Interbody Fusion Device (Copperhead®). The King Cobra® was developed specifically for the cervical spine as a lowprofile plating option to address the problems of cage migration, reduce surgical time, and minimize vascular injury.

DEMOGRAPHIC

# Patients: 81

Males

41

Females

40

Median Age (yrs.)

53 (20-72)

Median Wt. (lb.)

180 (120-280)

DIAGNOSIS Cervical HNP

45

Cervical Stenosis

36

Trauma; Infection

0

COMORBIDITIES Smoker

14

Diabetic

3

Previous Fusions (LEV)



1, 2, and 3 level King Cobra® Cervical Plate

PURPOSE: The purpose of this study is to demonstrate the very early results of the King Cobra® in regard to no screw back-out, screw breakage, plate breakage, any problems with the Twister, and prevention of migration of the cervical cage.

2 4 3 4 1

(C4-C5) (C5-C6) (C4-C7) (C5-C7) (C6-C7)

Pseudoarthrosis (LEV)

1 (C4-C5)

HIV

1

HTN

21

Page 1 of 12

DEVICE DESCRIPTION: The King Cobra® can be used as an adjunct device to supplement anterior cervical fixation. The plate consists of titanium, is available in 1, 2, 3, and 4 levels, and has a thickness of 2.2mm. The King Cobra® screws have 14 degrees of conical rotation with available sizes: 12mm, 14mm, and 16mm length with 4.0mm or 4.25mm diameter. METHODS: This study examines 81 patients, with 90 plates, from 3/17/11 to present, who were candidates for Anterior Cervical Interbody Fusion. All patients were consecutive. Diagnoses include cervical disc herniation and cervical stenosis. All devices were inserted using a left anterior approach. All patients received an ES® Anterior Cervical Interbody Fusion Device Copperhead® implant. Radiographical assessments include plain x-rays at: 2 wks, 6 wks, 3 mo and 6 mo.

Plate Level

Total

1 Level (#CS)

C3-C4 (5) C5-C6 (4) C6-C7 (2) C7-T1 (5)

16

2 Level (#CS)

C3-C5 (7) C4-C6 (6) C5-C7 (34)

47

3 Level (#CS)

C3-C6 (7) C4-C7 (13) C5-T1 (1)

21

4 Level (#CS)

C3-C7 (5) C4-T1 (1)

6

Plate Total Screw Size

90 Total

TECHNIQUE: Surgeon MUST review technique 4.0 x 12mm 26 manual prior to insertion. Begin by exposing the 4.0 x 14mm 19 anterior cervical spine and perform a discectomy or corpectomy of the correct level. Place the graft 4.0 x 16mm 5 so that it is flush or below the anterior margin of the vertebral body. Anterior plating is applied only 4.25 x 12mm 20 after adequate grafting. Confirm the vertebral levels 4.25 X 14mm 482 to be instrumented using fluoroscopy. Remove the anterior osteophytes to allow the plate to lie flush on 4.25 x 16mm 31 the true anterior cortex of the vertebral body. Select Screw Total 583 the appropriate length anterior cervical plate. Once the appropriate sized plate has been selected, use the plate holder to grip the plate and check to ensure that the plate fits the anatomy. 1, 2, 3, and 4 level plates are available. The plate should be positioned centered on the midline and should not overlie adjacent non-fused disc segments. The caudal and cephalad screw holes should be placed as close to the graft site without compromising the vertebral endplate. Use a standard operating room burr to penetrate the anterior cortex of the vertebral body. Start with the cephalad hole of the plate. The drill guide consists of one cannula. The drill bits are 1.75mm in diameter and correspond to screw length. The drill bit shaft is attached to the AO drive ratchet handle. Assemble the drill bit into the drill guide. The tip of the drill guide should be seated into the cervical plate hole. Apply light downward pressure on the drill guide and rotate the drill clockwise.

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Advance the drill into the bone until the stop of the drill makes contact with the back of the drill guide. Remove the drill from the bone by turning the drill counter-clockwise while pulling back on the drill. Once the screw hole has been prepared, select the appropriate screw length and diameter. Screws are available in 12, 14, and 16mm lengths and 4.0 and 4.25mm in diameter. The screw is attached to the screwdriver. Turn the screwdriver clockwise and insert the screw into the bone and plate screw hole. Tighten the screws so that the plate is seated evenly and flush to the anterior cortex of the cervical spine. Since all screws are self tapping, tapping is not required. Intraoperative radiographs or fluoroscopy should be used to check plate position before screw insertion. The screws should be contained in the vertebral body and not penetrate into the spinal canal or adjacent disc space. The locking cap driver is placed on the locking cap. Rotate the locking cap driver clockwise 90 degrees. The locking cap edges should cover the head of the cervical screw. Obtain AP and lateral radiographs for final plate and screw position. For removal, attach the locking cap driver on the locking cap and rotate it counter-clockwise 90 degrees. Attach the cervical screwdriver into the cervical screw and remove the screw. After all cervical screws have been removed, then remove the cervical plate. Reference the King Cobra® technique manual on the ES® website.

RESULTS: Of the 81 patients included in the study, each patient completed a 2 and 6 week and 3 and 6 month follow up based on date of surgery. Lateral and AP x-rays were taken at that time. The O.R. time for the King Cobra® was 45-230 minutes (120 minutes). Estimated blood loss was 12-400cc (100cc). No patient needed re-operation and there was no plate breakage. There was no migration of the Copperhead®. There was no screw back-out, no screw breakage, no malfunction with the Twister, and no infection or dysphagia.

Complications Screw back-out

0

Screw breakage

0

Twister malrotated

0

Twister popped off

0

Cage Migration

0

Plate broke

0

Dysphagia

0

Infection

0

DISCUSSION: This preliminary study has shown that the Eminent Spine Anterior Cervical Plate King Cobra® is a device that can be safely implanted. This study has demonstrated that the King Cobra® is a safe and effective product. The Twister locking mechanism has also been shown to be a safe, easy, and effective way to lock the screw into the Cervical Plate. Clinical studies are currently being performed to further evaluate the product.

Page 3 of 12

1 Level: C6 - C7 King Cobra® Cervical Plate Copperhead® Cervical Cage ✴49

y/o WF with Radiculopathy and Triceps Weakness

C6 C7

Pre-Op

Post-Op

Page 4 of 12

1 Level: C4 - C5 King Cobra® Cervical Plate ® Copperhead Cervical Cage ✴

41 y/o WF 2004 C5-C6 Fusion and Plate Current C4-C5 Radiculopathy

C4

C4

Pre-Op

C6

Post-Op Page 5 of 12

2 Level: C5 - C7 King Cobra® Cervical Plate ® Copperhead Cervical Cage ✴ 50y/o

WF with Severe Left Arm Radiculopathy and Triceps Weakness

C5 C6 C7

Pre-Op

Post-Op

C5 C6 C7

Page 6 of 12

2 Level: C5 - C7 King Cobra® Cervical Plate ® Copperhead Cervical Cage ✴45y/o

WF with Severe Left Arm Radiculopathy and Triceps Weakness

C5 C6

C7

Pre-Op

Post-Op

Texas Twister Page 7 of 12

2 Level: C5 - C7 King Cobra® Cervical Plate ® Copperhead Cervical Cage

✴ 64y/o

WM with Cervical Disc Disease and Right Arm Radiculopathy

C5 C6 C7

Pre-Op

Post-Op

C5 C6 C7

Page 8 of 12

2 Level Revision: C3 - C5 King Cobra ® Cervical Plate ® Copperhead Cervical Cage ✴ 63

y/o BM with Pseudoarthrosis and Cervical Stenosis

C3 C5

Pre-Op

Post-Op

C3

C5

Page 9 of 12

3 Level: C4 - C7

King Cobra® Cervical Plate ® Copperhead Cervical Cage ✴ 37y/o

BF with Multi-Level Stenosis and Right Arm Radiculopathy

C4 C5 C6 C7

Pre-Op

Post-Op

C4 C5 C6 C7

Page 10 of 12

3 Level: C4 - C7 King Cobra® Cervical Plate Copperhead® Cervical Cage ✴ 49

y/o WF with Multi-Level Stenosis

C4

Pre-Op

C4

C7

Post-Op

Page 11 of 12

4 Level: C3 - C7 King Cobra® Cervical Plate ® Copperhead Cervical Cage ✴ 58

y/o WM with Degenerative Disc Disease and Multi-Level Stenosis C3 C3 C4 C5 C6 C7 C7

C3 C4 C5 C6 C7

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